The impact of sleep loss and sleep disorders on the health, social and economic well being of Americans is enormous. Yet our knowledge about the control and function of sleep remains severely limited, and based largely on studies where subjects are tethered, with significant behavioral side- effects. Thus, compact, implantable recording systems have become a major factor in sleep studies, especially in small transgenic mouse models where tethering is not practical. Existing telemetry systems are severely limited in the amount of information they can gather, and are not conducive for most studies. To address this need, we have assembled an interdisciplinary team to address four specific aims. First, we will develop a flexible electrode array that can be chronically implanted on the cortical surface of neural tissue. Traditional rigid electrode arrays require large skull openings. The flexible array has the advantage of minimal tissue trauma because only a slot in the skull is needed to insert the flexible array. One major drawback of multi-channel recordings comes from the large number of wires required for 16 to 256 or more channels of electrophysiology. Signals multiplexing can help, but available components including amplifiers, filters and multiplexers are comparatively large. Thus, our second aim will develop a miniature analog-system-on-a-chip, including preamplifiers, filters, multiplexer and 16 bit analog-to-digital converter for sampling 16 to 256 channels up to 32 kHz per channel. The chip will initially require only 5 wires for a serial digital connection and will weigh less than 1 gram. Our third aim will be to implement high speed wireless technology to allow the serial digital data to be transmitted directly from the acquisition chip to our computer interface card without the use of wires. Recent developments in digital wireless technology have allowed unprecedented data rates through transmitted signals. However, in order for wireless technology to be effective, our fourth aim will focus on an implantable power source enabling fully untethered recordings. Different power source technologies will be explored including battery and magnetic inductance. The technologies developed within this proposal will provide powerful new tools for neuroscience when many channels of electrophysiology, EEC, SEP and multi-unit electrodes are required in freely behaving animals, especially small rodents. The new technology is particularly important for wireless medical devices that require many channels with high data rates.